The present invention relates to an apparatus and method for monitoring operation of a temperature control apparatus and, more particularly, to an apparatus and method for determining temperature control apparatus failure.
Temperature control apparatuses are commonly mounted on trucks, trailers, vans, railcars, shipping containers, and the like to control the temperature of an interior load space. In general, these temperature control apparatuses include a compressor, a condenser, an expansion valve, and an evaporator. The compressor operates to raise the pressure and temperature of a refrigerant and the condenser operates to condense the refrigerant from a high-pressure gaseous state to a liquid. The expansion valve typically controls the flow of the liquid refrigerant to the evaporator. The evaporator includes an evaporator housing and evaporator coils that extend through the evaporator housing.
During operation, relatively warm air is drawn into the evaporator housing and is directed across the evaporator coil. The refrigerant flows through the evaporator coils and absorbs heat from the air in the evaporator housing, and in this way pulls down the temperature of the air before the air is exhausted from the evaporator housing to maintain the temperature of a conditioned space at or near a set point temperature.
Drive units, such as, for example, internal combustion engines, are commonly used to power temperature control apparatuses. Typically, the drive unit provides power to one or more of the compressor, fans, and a controller.
The present invention provides a temperature control apparatus, such as a transport refrigeration unit. In one construction, the temperature control apparatus includes a refrigeration circuit extending between a compressor, a condenser, and an evaporator. A drive unit is drivingly coupled to the compressor. The drive unit has a fuel supply, a number of cylinders, a fuel line fluidly connecting the fuel supply and the cylinders, and a rack positioned along the fuel line. The rack is moveable to control a flow of fuel between the fuel supply and at least one of the cylinders. The rack has a position sensor arranged to record a rack position. A controller is in communication with the compressor and the position sensor. The controller is operable to identify malfunctions of the temperature control apparatus based on the rack position.
In some constructions, the temperature control apparatus includes a temperature sensor in thermal communication with the fuel supply to record a fuel supply temperature. The temperature sensor is in communication with the controller and the controller uses the fuel supply temperature to identify malfunctions of the temperature control apparatus.
In other constructions, the refrigeration circuit is in thermal communication with a load space having load space air and the temperature control unit includes a housing at least partially enclosing the refrigeration circuit. The housing defines an inlet and an outlet. Load space air is moveable through the inlet and the outlet. A first temperature sensor is positioned adjacent to the inlet and is operable to record a first temperature. A second temperature sensor is positioned adjacent to the outlet and is operable to record a second temperature. The controller is in signal receiving communication with the first and second temperature sensors.
The present invention also provides a method of monitoring operation of a temperature control apparatus. The method includes directing air across the evaporator, adjusting the rack, recording a rack position with the position sensor, calculating a fuel consumption rate using the rack position, calculating an actual output power of the drive unit using the fuel consumption rate, calculating an expected output power of the drive unit, and comparing the actual output power of the drive unit and the expected output power of the drive unit to predict malfunctions of the temperature control apparatus.
In some constructions, the temperature control apparatus includes a temperature sensor in thermal communication with the condenser and in communication with the controller. In some aspects of the invention, the method includes sensing a temperature of the condenser, and calculating the expected output power of the drive unit includes using the temperature of the condenser.
In other aspects, the method includes directing air across the evaporator, recording a fuel flow rate with the sensor, calculating an actual output power of the drive unit using the fuel flow rate, calculating an expected output power of the drive unit, and comparing the actual output power of the drive unit and the expected output power of the drive unit to predict malfunctions of the temperature control apparatus.